Cable management to flown monitors

[Tom]

Hi,

We want to lower and raise a cluster of three monitors over the stage during a show.

The monitors are rigged to a bit of truss which will be on motors.

 

I was thinking to manage power using a retractable cable reel but what about signal?

 

Does anybody have, or can anybody point me at, a similar retractable reel for video signal?

Or is there another solution?

 

Travel is about 6m (though 10m would mean I could get them to the deck to service them).

Its an open, studio type set up so while I could do some form of cable loop there's not much in the way of Off Stage in which to do it. Plus this is in the middle of the space with the nearest wall about 8m away so not very convenient.

 

Budge is of course tight and I need a solution to rig next week.

 

Many Thanks

 

T

 

Edit to say - I'm in London if anybody was offering a solution.

[mac.calder]

I have seen a standard cable reeler with slip rings used for SDI - but it cetainly didn't pass HD-SDI.

 

What about energy chain or a jacobs ladder?

[Tom]

HD might not be a problem. But your being on the other side of the world might.

(I neglected to say, I'm in London)

 

What is Energy Chain?

 

T

[mac.calder]

 

Energy Chain.

 

Jacobs Ladder

[Robin D]

If it's HDMI something like this would do the trick. Other types are available from this and other suppliers.

 

You could also use Powerline type products and put it over cat5 if you are sending clean power up... which I assume you are.

[Seano]

I was thinking to manage power using a retractable cable reel but what about signal?

 

You have motor cables to manage too don't you?

 

Loom everything together as neatly as poss. Then if you have sufficient headroom above the truss's high trim you could have an additional motor as a pick that moves with the truss lifting & lowering a 'swag' of cable loom. For 10m of travel, you need 5m up (5m down again) when the truss is out, which translates to 10m down when the truss is in.

 

Otherwise the usual way to deal with it would be chain sliders on one of the hoists on your truss (which will also require an additional pick, truss, or something to fly your cables over to within a couple of feet of that hoist). Each slider takes a loop of 1m or so of cable loom. It's fairly routine stuff for any of the lighting companies touring music these days.

 

There is a bit of a knack to spacing the sliders so the whole thing doesn't go horribly pear shaped, if you know what you're doing it's easier to do than it is to describe in writing, if you don't you probably need a bit of help from someone who does.

[kitlane]

I was thinking to manage power using a retractable cable reel but what about signal?

 

You have motor cables to manage too don't you?

 

 

Only if it's motors down.

[Seano]

Only if it's motors down.

 

Indeed. In the absence of more specific info from the OP that's merely an assumption on my part because most of the time you'd be daft not to.

 

Inverted hoists still need cables running to them and unless the design of the venue is particularly accommodating - a nice well organised accessible grid for example - it's a job that invariably turns out to be a pain in the arse. (And one that involves some work at height that would, from a risk-assessment point of view, be better eliminated.)

[Tom]

Briefly, just to bring clarity, yes motor up for esthethitc reasons and for less cable management.

Grid access is good plus we have a scissor to rig from.

 

T

[Seano]

Ok.

 

Chain sliders would probably still be a good option. You could loom mains and signal and manage them both together, drop the loom from the grid about two feet or so from the hoist. The bottom sliders (and whatever slack cable remains) rests on the hook block, you could keep your cable loops clear of the truss by using a deep pick-up (which also helps with the stability of the truss) or a short stinger below the hook.

 

One slider for each meter or so of cable, carefully arranged so the loops are nice and even. Best way to do that is start with the truss down, follow it up on the scissor lift attaching cable sliders as you go from the bottom, taking care that they're spaced evenly enough that no loop hangs below the bottom of the one underneath it.

 

Alternatively if you have the mains sorted and you're looking for something to manage a signal cable only, various Heath Robinson arrangements of pulleys, string and/or sandbags spring to mind that would do the job more or less reliably for pennies.

 

Here's a wholly untested and quite possibly completely hatstand suggestion that might avoid the need to drop a loop of cable or manage any slack below the grid <napkin-cad drawing follows>:

 

http://www.deepsoup.f2s.com/BR/cabledrop.jpg

 

Cable drops over a pulley to truss. From there over to some point where you can safely dangle a sandbag below the grid, you string up a catenary and starting the requisite length of cable away from this pulley, loop the same amount again between maillons/shackles/shower curtain rings/whatever on the catenary. Same arrangement you'll often see used to artfully tangle a comms cable on a fly floor.

 

Dangle a weight on a string below the grid somewhere near the opposite end of the catenary, to maintain a constant tension on a string which takes up the slack.

Usual caveats apply - if you try this and end up killing half the cast and burning the venue down you ain't seen me roight? :)

[sunray]

The way I used to do this for night clubs light rigs was to construct a 'tank' on top of the truss and the cable would happily fold itself into that.

Mostly the cable would be a 1.5mm 12 core or two and DMX which would all be bunched together using self amalgamating tape every 18" or so. Too frequently and it gets too stiff, not enough and the cables separate and tangle.

Not cable ties as they snag and pvc tape is not hardy enough.

The tank would typically be 3' square and 1' high or so and in our case tended to be expanded metal and angle ali.

 

I have also seen it done with a sack mounted on a hoop (Like the chain hoist bags but bigger) but you need to put twists in the cable so it will coil.

[Tom]

Just for completion...

So in the end we rigged an inertia real fall arrest block as a back up for the motors.

We loomed the power and data cables and then cable tied small maillons (because that's what we had) every 750mm or so to the cables and connected them around the inertia real wire. The cables looped nicely as the truss went in and out. So relatively similar to Seano's concept but vertical rather than horizontal.

We taped a breakaway loop at the top so that in the event of something getting snagged that would drop before the cables started ripping out of anything important or expensive.

 

For a one off gig it worked fine.

 

T

[Seano]

So relatively similar to Seano's concept...

 

Exactly the same as chain sliders, you just didn't have them on a chain.

 

Glad it worked out well for you. :)